. Electroanalytical properties of unmodified and modified by polyaniline and by CuO nanoparticles solid-contact potentiometric sensors which are based on associates of tetradecylammonium with complex compounds of silver (I) with cephuroxime, cephotaxime and cephazoline Ag(?-lac)2TDA in solutions of corresponding antibiotics were studied. It was revealed that Ag(?-lac)2TDA –based sensors had no specificity to the basic ion but showed sensitivity to other cephalosporins.